title: Gentamicin conditioning confers auditory protection against noise trauma.
abstract: Auditory conditioning consists of the pre-exposure to low levels of a potential harmful agent to protect against a subsequent harmful presentation. The agent that was first tested was noise. This paradigm was more recently successfully tested with other agents. Nonetheless, the vast majority of the studies utilize the same agent to condition and to cause the trauma. The aim of this study was to verify whether conditioning with an agent different from the agent used to cause the trauma can also be effective. Thus, the following groups were organized: group Cont, which is the noise trauma control group, was exposed to 110-dB broadband noise centered at 4 kHz for 72 h; group Gent, which is the gentamicin conditioning control group, was administered 30 mg/kg of gentamicin daily for 30 consecutive days; and group Expt was conditioned with gentamicin similarly to group Gent and then subjected to a noise trauma similarly to group Cont. The animals were functionally and morphologically evaluated through the measurement of the auditory brainstem response and scanning electron microscopy, respectively. The following variables were investigated: outer hair cell injury and auditory threshold shift. The group that was conditioned with the drug exhibited significantly less outer hair cell damage, 10.8 and 22.9%, respectively (p = 0.0146), although did not maintain the proper functioning of the auditory system. We, therefore, conclude that conditioning with a different agent from that used to cause the trauma is effective, which suggests that both agents that were used promote similar mechanisms of self-protection.
authors.affiliation: Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Av. Bandeirantes, 3900, 12 andar, Monte Alegre, Hospital das Clinicas de Ribeirão Preto (HCFMRP), São Paulo, 14049-900, Brazil, alexstrose@usp.br.
authors.forename: Alex
authors.initials: A
authors.lastname: Strose
authors.forename: Gleice Cristina
authors.initials: GC
authors.lastname: Colombari
authors.forename: Maria
authors.initials: M
authors.lastname: Rossato
authors.forename: Miguel Ângelo
authors.initials: MÂ
authors.lastname: Hyppolito
authors.forename: José Antônio Aparecido
authors.initials: JA
authors.lastname: de Oliveira
mesh_terms: D000161:Acoustic Stimulation / Q000009:adverse effects; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001309:Auditory Threshold / Q000502:physiology; D003051:Cochlea / Q000187:drug effects; D004195:Disease Models, Animal; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005839:Gentamicins / Q000494:pharmacology* / Q000627:therapeutic use; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D006317:Hearing Loss, Noise-Induced / Q000209:etiology / Q000517:prevention & control*; D008297:Male; D008855:Microscopy, Electron, Scanning; D009622:Noise / Q000009:adverse effects*; D065129:Pre-Exposure Prophylaxis
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins